Knife sharpener



FIG. 1 is a front elevational view of a knife sharpener showing my newdesign;

FIG. 2 is an auxiliary left side elevation view thereof, wherein thefinger guard is removed to disclose the grip surface;

FIG. 3 is a right side view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a left side view thereof.

The rear elevation view is a mirror image of the front elevation viewillustrated in FIG. 1. The broken line portions of the disclosure arefor illustrative purposes only and form no part of the claimed design.

The ornamental design for a knife sharpener, as shown and described.